US20060240919A1 - Bicycle transmission - Google Patents
Bicycle transmission Download PDFInfo
- Publication number
- US20060240919A1 US20060240919A1 US11/403,967 US40396706A US2006240919A1 US 20060240919 A1 US20060240919 A1 US 20060240919A1 US 40396706 A US40396706 A US 40396706A US 2006240919 A1 US2006240919 A1 US 2006240919A1
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- US
- United States
- Prior art keywords
- chain
- guide
- transmission
- sprocket
- bicycle
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Abandoned
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Classifications
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B62—LAND VEHICLES FOR TRAVELLING OTHERWISE THAN ON RAILS
- B62M—RIDER PROPULSION OF WHEELED VEHICLES OR SLEDGES; POWERED PROPULSION OF SLEDGES OR SINGLE-TRACK CYCLES; TRANSMISSIONS SPECIALLY ADAPTED FOR SUCH VEHICLES
- B62M11/00—Transmissions characterised by the use of interengaging toothed wheels or frictionally-engaging wheels
- B62M11/04—Transmissions characterised by the use of interengaging toothed wheels or frictionally-engaging wheels of changeable ratio
- B62M11/14—Transmissions characterised by the use of interengaging toothed wheels or frictionally-engaging wheels of changeable ratio with planetary gears
- B62M11/145—Transmissions characterised by the use of interengaging toothed wheels or frictionally-engaging wheels of changeable ratio with planetary gears built in, or adjacent to, the bottom bracket
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B62—LAND VEHICLES FOR TRAVELLING OTHERWISE THAN ON RAILS
- B62M—RIDER PROPULSION OF WHEELED VEHICLES OR SLEDGES; POWERED PROPULSION OF SLEDGES OR SINGLE-TRACK CYCLES; TRANSMISSIONS SPECIALLY ADAPTED FOR SUCH VEHICLES
- B62M9/00—Transmissions characterised by use of an endless chain, belt, or the like
- B62M9/04—Transmissions characterised by use of an endless chain, belt, or the like of changeable ratio
Abstract
To improve the operating performance of a chain. A bicycle transmission includes an alignment guide located between a drive sprocket and a transmission sprocket cluster for aligning a stagnant chain. The alignment guide consists of a guide roller having an outer circumferential surface for guiding the stagnant part of the chain in a way to align it. The outer circumferential surface has, in the axial direction, a large diameter portion on the side of a transmission sprocket with the smallest outside diameter, and a small diameter portion on the side of a transmission sprocket with the largest outside diameter, which is smaller in diameter than the large diameter portion. While the chain is not stagnant, the chain, wound around a transmission sprocket, contacts the small diameter portion.
Description
- The present application claims priority under 35 USC 119 to Japanese Patent Application No. 2005-118931 filed on Apr. 15, 2005 the entire contents of which are hereby incorporated by reference.
- The present invention relates to a bicycle transmission which changes the speed by shifting a chain among plural transmission sprockets.
- AN example of a bicycle transmission that changes the speed by shifting a chain among plural transmission sprockets is disclosed in JP-A No. 155280/2004 which includes a drive sprocket connected through a one-way clutch to a crankshaft disposed between body frames with a plurality of transmission sprockets connected to an output shaft for driving a rear wheel. A chain is wound around the drive sprocket and a transmission sprocket. A gear shift mechanism has a derailleur arm which rotatably supports a guide pulley for guiding the chain to a transmission sprocket so that a gear change operation moves the derailleur arm together with the guide pulley in the axial direction of the derailleur to shift the chain from one transmission sprocket to another.
- The chain around which the drive sprocket and transmission sprocket are wound may be prevented from operating smoothly due to the rotating condition of the drive sprocket and transmission sprocket based on the bicycle operating condition or the axial movement of the guide pulley induced by the gear shift mechanism. This phenomenon often happens when the transmission is located between the front wheel and the rear wheel, namely in the center of the body and close to the drive sprocket and transmission sprocket.
- For example, as far as the chain on the drive sprocket wind-in side is concerned, it may happen that when the drive sprocket is driven by the crankshaft, it is tight, but when the transmission sprocket is driven by the drive wheel as while the bicycle is freewheeling, its tension decreases and it becomes loose and partially gets folded and stagnant in the drive sprocket wind-in portion, thus preventing smooth operation of the chain.
- Also, when the transmission sprocket is rotating in the reverse direction during a backward movement of the bicycle or it is stopped while the bicycle is stationary, namely the transmission sprocket is not rotating normally, if a gear shift operation is carried out and the guide pulley moves axially, a considerable torsion occurs on the chain between the transmission sprocket and the guide pulley because the transmission sprocket does not move axially, causing a rapid rise in friction between neighboring links. This friction prevents the chain from sagging along the profile of the guide pulley. Consequently the chain will come off the guide pulley outward in its radial direction so that the chain cannot operate smoothly.
- In addition, regarding a tension pulley which has teeth to engage with the chain, when it moves axially together with the guide pulley upon gear shift operation, a chain torsion may occur on its wind-in side. Since the chain's axial movement is limited by the tension pulley's teeth, this torsion, which occurs in a limited space in the circumferential direction of the tension pulley, becomes large, which increases the friction between neighboring links and thus prevents the chain from sagging along the profile of the tension pulley. As a result, a smooth chain operation and a smooth gear shift will be prevented.
- The present invention has been made in view of the above circumstances and an embodiment of the present invention is intended to improve the operating performance of the chain and an embodiment of the present invention is intended to improve the operability of the transmission.
- According to an embodiment of the present invention, a bicycle transmission includes a drive sprocket which is rotated by a crankshaft with a transmission sprocket cluster which is disposed in the axial direction and composed of a plurality of transmission sprockets with different outside diameters. A chain is wound around the drive sprocket and the transmission sprockets with a shift mechanism for shifting the chain among the transmission sprocket cluster as described in gear shift operation. An alignment guide is located between the drive sprocket and the transmission sprocket cluster to align a stagnant part of the chain. The alignment guide consists of a guide part with a guide surface which guides the stagnant part of the chain in a way to align it. The guide surface, in the axial direction, is provided with a basic portion located on the side of the transmission sprocket with the smallest outside diameter, and a retreated portion which is located on the side of the transmission sprocket with the largest outside diameter and more retreated inside or outside the chain than the basic portion. The chain contacts the retreated portion while the chain is not stagnant.
- According to an embodiment of the present invention, the stagnant part of the chain is guided by the guide part of the alignment guide to reach the alignment hole as aligned, resulting in resolution of the stagnancy, which prevents the stagnant part from being caught in the drive sprocket without resolving the stagnancy. In addition, since the chain, which contacts the guide part while it is not stagnant, contacts the retreated portion of the guide part and therefore the chain curves less than when it contacts the guide surface without a retreated portion. Thus, the friction applied from the guide part to the chain is reduced.
- According to an embodiment of the present invention, the guide part is a guide roller having an outer circumferential surface which constitutes the guide surface with the retreated portion being a small diameter portion with a diameter smaller than the basic portion. The chain wound around the transmission sprocket with the largest outside diameter contacts the small diameter portion while the chain is not stagnant.
- According to this, rotation of the guide roller further smoothens the guidance to align the stagnant part and accelerates the resolution of the stagnancy. In addition, the friction applied to the chain wound around the largest outside diameter transmission sprocket from the small diameter portion as the retreated portion is further reduced.
- According to an embodiment of the present invention, the alignment guide consists of a first guide as the guide part and a second guide having a second guide surface which forms an alignment hole through which the chain passes, in conjunction with a first guide surface as the guide surface of the first guide. In addition, the second guide surface has a projection protruding toward the retreated portion in order to maintain the width of the alignment hole in the direction of inward or outward movement of the chain almost constant at any axial position.
- According to this, due to the projection, the width of the alignment hole with the presence of the retreated portion is almost equal to the width of the alignment hole defined by the basic portion and the second guide surface's portion other than the projection, and therefore alignment takes place in the retreated portion properly.
- According to an embodiment of the present invention, a bicycle transmission includes a drive sprocket which is rotated by a crankshaft with a transmission sprocket cluster including a plurality of transmission sprockets disposed in the axial direction. A shift mechanism shifts the chain among the transmission sprocket cluster as described in gear shift operation. The shift mechanism includes a guide pulley around which the chain is wound, and the guide pulley moving axially guides the chain wound around one active sprocket selected from among the transmission sprocket cluster. It has a limiting member for restricting disengagement of the chain from the guide pulley and the limiting member is located between the guide pulley and the active sprocket, outward in the radial direction of the guide pulley.
- According to this, a torsion which occurs in the chain due to axial movement of the guide pulley upon the gear shift operation increases the friction between links of the chain and makes it difficult for the chain to sag along the guide pulley. Thus, when the chain is about to disengage or disengages from the guide pulley, the chain contacts the limiting member and restricts the disengagement of the chain.
- According to an embodiment of the present invention, the limiting member is located between the rotational centerline of the crankshaft and the rotational centerline of the transmission sprockets, in a position to overlap the transmission sprockets when viewed sideways.
- According to this, since the limiting member is in a position to overlap the transmission sprockets when viewed sideways, it is located in the space between the rotational centerline of the crankshaft and the rotational centerline of the transmission sprockets, and the distance between the crankshaft and the transmission sprockets need not be increased due to the presence of the limiting member.
- According to an embodiment of the present invention, an alignment guide which is located between the drive sprocket and the transmission sprocket cluster to align a stagnant part of the chain is provided and the limiting member is molded integrally with the alignment guide.
- According to this, since the limiting member is molded integrally with the alignment guide, there is no increase in the number of components.
- According to an embodiment of the present invention, a bicycle transmission includes a drive sprocket which is rotated by a crankshaft with a transmission sprocket cluster including a plurality of transmission sprockets disposed in the axial direction. A shift mechanism shifts the chain among the transmission sprocket cluster as described in gear shift operation. The shift mechanism includes a guide pulley around which the chain is wound and a tension pulley which gives tension to the chain with the guide pulley moving axially together with the tension pulley upon a gear shift operation for guiding the chain wound around one active sprocket selected from among the transmission sprocket cluster. A part of the tension pulley contacts the chain consists of a surface on which the chain can slide axially.
- According to this, since the chain axially moves across an extensive area in the circumferential direction of the tension pulley during axial movement of the tension pulley upon gear shift operation, the torsion in the chain decreases and the friction between links of the chain decreases as well. Thus, the chain easily sags along the contact part of the tension pulley and operates on the tension pulley smoothly.
- According to an embodiment of the present invention, a transmission case which supports the crankshaft and the transmission sprocket cluster is provided and the transmission case is located between the front wheel and rear wheel of the bicycle.
- In the transmission which is located between both wheels of the bicycle, or in the center of the bicycle, the drive sprocket and the transmission sprocket cluster are adjacent to each other and the torsion in the chain which occurs upon a gear shift operation tends to be considerable. However, the tension pulley substantially reduces the torsion and therefore the chain operates on the tension pulley smoothly.
- According to an embodiment of the present invention, the following effect is provided. Namely a stagnant part of the chain is prevented from being caught in the drive sprocket. Since the friction applied to the chain which contacts the guide part is reduced, performance of the operation of the chain is improved.
- According to an embodiment of the present invention, the resolution of the stagnancy of the chain is accelerated and also the friction applied from the guide roller to the chain wound around the largest outside diameter transmission sprocket is further reduced, so that the operating performance of the chain is further improved and the operating performance of the bicycle with the largest outside diameter transmission sprocket is improved.
- According to an embodiment of the present invention, since alignment takes place properly even in the retreated portion, the friction from the guide part is reduced and proper alignment by the alignment guide is ensured.
- According to an embodiment of the present invention, since the limiting member prevents or restricts disengagement of the chain, the operating performance of the chain on the guide pulley is improved.
- According to an embodiment of the present invention, since the limiting member is located in the space between the rotational centerline of the crankshaft and the rotational centerline of the transmission sprockets, it is possible to provide the limiting member while keeping the compactness of the transmission.
- According to an embodiment of the present invention, the transmission is provided with a limiting member that can be obtained without an increase in the number of components.
- According to an embodiment of the present invention, since the chain operates on the tension pulley smoothly, the operating performance of the chain is improved.
- According to an embodiment of the present invention, the transmission is located in the center of the bicycle. Thus, the operating performance of the chain is improved.
- Further scope of applicability of the present invention will become apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description.
- The present invention will become more fully understood from the detailed description given hereinbelow and the accompanying drawings which are given by way of illustration only, and thus are not limitative of the present invention, and wherein:
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FIG. 1 is a schematic left side view of a bicycle with a transmission to which the present invention is applied; -
FIG. 2 is a fragmentary sectional view showing the transmission ofFIG. 1 with the second case removed. The solid lines indicate the condition at the highest speed gear position and the two-dot chain lines indicate the condition at the lowest speed gear position; -
FIG. 3 is a sectional view taken along the line III-III inFIG. 2 showing part of the derailleur. The solid lines indicate the condition at the highest speed gear position and the two-dot chain lines indicate the condition at the lowest speed gear position; -
FIG. 4 (a) is a sectional view taken along the line IV-IV inFIG. 2 showing part of the derailleur. The solid lines indicate the condition at the highest speed gear position and the two-dot chain lines indicate the condition at the lowest speed gear position; -
FIG. 4 (b) is an enlarged view of a major part inFIG. 4 (a); -
FIG. 5 (a) is a right side view of the sprocket cover of the transmission ofFIG. 1 ; -
FIG. 5 (b) is a view taken from arrow B inFIG. 5 (a); -
FIG. 6 is an enlarged view of the alignment guide and its vicinity inFIG. 2 ; -
FIG. 7 is a sectional view taken along the line VII-VII inFIG. 2 ; -
FIG. 8 is a view of the first member of the alignment guide, taken from arrow VIII inFIG. 6 ; -
FIG. 9 is a view which illustrates that the chain is stagnant in the vicinity of the alignment guide; -
FIG. 10 (a) is an enlarged view of the tension pulley and its vicinity inFIG. 4 (a); and -
FIG. 10 (b) is a view of the tension pulley, taken from arrow B inFIG. 10 (a). - Referring to
FIG. 1 , a bicycle B is equipped with a transmission T as described in the present invention that includes a body frame F with a pedaledcrankshaft 12 and a transmission system which transmits power of thecrankshaft 12 to a rear wheel Wr as a drive wheel. This transmission system includes a transmission T, anoutput shaft 15 which is rotated by power after speed change by the transmission T and a driving power transmission mechanism which transmits power of theoutput shaft 15 to the rear wheel Wr. - The body of the bicycle B has a body frame F and a
swing arm 10. The body frame F includes a head pipe 1 steerably supporting front forks 6 which pivotally support a front wheel Wf at its bottom and hashandlebars 7 at its top. A bifurcated main frame 2 stretches downwardly and obliquely rearwardly from the head pipe 1. A downtube 3 stretches downwardly and obliquely rearwardly from the front end of the main frame 2. A pair of under tubes 4 (left and right) connect the rear end of thedown tube 3 with the pair of rear ends of the main frame 2. A saddle frame 5 stretches from the main frame 2 and supports thesaddle 8. - In the specification and the claims, top, bottom, front, rear, left and right correspond to the bicycle's top, bottom, front, rear, left and right, respectively. Also, the “axial direction” means the direction of the rotational centerline L3 of the
transmission sprockets 41 to 47 and an the expression “viewed sideways” means that something is “viewed from the axial direction.” - On a
pivot shaft 9, seeFIG. 4 (a), that is provided on a pair ofrear portions 2 a of the main frame 2, the front ends of a pair of swing arms (left and right) 10 which pivotally support the rear wheel Wr at the rear ends are swingably supported through abearing 11. Theswing arms 10 are both connected through the suspension S to the main frame 2 so that they can swing up or down around thepivot shaft 9 together with the rear wheel Wr. - The transmission T, and a
main shaft 12 a of thecrankshaft 12 and theoutput shaft 15 which are rotatably supported by the transmission T are located in the center of the bicycle B, namely, between the front wheel Wr and rear wheel Wr, at the bottom of the body frame F, in the space between therear portions 2 a of the main frame 2 and theunder tubes 4. The above driving power transmission mechanism is located on the right of the transmission T. - Referring to FIGS. 2 to 4(a) as well, the transmission T has a
metal transmission case 20 that includes a pair of cases (left and right). Afirst case 21 and asecond case 22 are provided which are liquid-tightly coupled through aseal member 23, seeFIG. 7 , by a bolt N1 atbosses transmission case 20 is fixed onto the main frame 2 and theunder tubes 4 at a pair of mounting tabs.FIG. 2 illustrates mounting tabs 211 b of thefirst case 21 that are formed at the peripheries of thecases FIG. 1 . - The
crankshaft 12 includes amain shaft 12 a that penetrates through the lower part of thetransmission case 20 in the left/right direction. A pair of crankarms 12 b are respectively coupled to themain shaft 12 a left and right ends that project outward from thetransmission case 20. Thecrankshaft 12 is rotatably supported by the first andsecond cases bearings 14. A pedal 13, seeFIG. 1 , is rotatably attached to each of thecrank arms 12 b. - The
output shaft 15 is disposed obliquely upwardly in front of themain shaft 12 a and thepivot shaft 9 is disposed almost just above themain shaft 12 a in a way that the rotational centerline L2 of theoutput shaft 15 and the centerline of swing of theswing arms 10 are parallel to each other and also to the rotational centerline L1 of thecrankshaft 12 and also they fall within the orbit of rotation of thecrank arms 12 b. Since themain shaft 12 a and theoutput shaft 15 are disposed between the front wheel Wf and rear wheel Wr, they are closer to each other than in a bicycle whose output shaft is coaxial with the rear wheel. - The
pivot shaft 9, which is fastened and fixed on the main frame 2, passes through a through hole in apivot collar 16 which axially touches thebosses second cases second cases pivot collar 16, which consists of axially disposed cylinders with different outside diameters, have a larger diameter than itscentral part 16 c with a small diameter. Due to the large diameter of theends pivot collar 16 is strong enough to bear the fastening load on thepivot shaft 9. In addition; due to the small diameter of thecentral part 16 c, thepivot collar 16 is lightweight and can avoid interference with thedrive sprocket 32 and the chain C to permit the construction of a compact transmission T. - Referring to
FIGS. 1 and 3 , theoutput shaft 15 housed in thetransmission case 20 has anend 15 a projecting to the right from thesecond case 22 and anoutput drive sprocket 17 as an output drive rotator that is coupled with theend 15 a. Anoutput chain 19 is provided as a flexible output endless transmission belt that is wound around thedrive sprocket 17. An output drivensprocket 18 is provided as an output driven rotator which is drivably connected with the rear wheel Wr. Thedrive sprocket 17, drivensprocket 18 andchain 19 constitute the above driving power transmission mechanism. - Referring to
FIGS. 1, 3 and 5, a syntheticresin sprocket cover 24 partially covers thedrive sprocket 17 and thechain 19 from above, behind and the right is attached to thetransmission case 20. Located within the orbit of crank arm rotation, thesprocket cover 24 includes atop wall 24 a for covering thedrive sprocket 17 and thechain 19 from above. Aback wall 24 b is located near themain shaft 12 a of thecrankshaft 12 and covers thedrive sprocket 17 from behind. Aside wall 24 c covers the right side. A pair of mountingbosses 24 d is provided through which bolts to be threaded into thesecond case 22 are passed. In addition, holes 25 a and 25 b through which thechain 19 is passed are made in thesprocket cover 24, between thetop wall 24 a and theback wall 24 b and between both the mountingbosses 24 d, respectively. Thesprocket cover 24 prevents the feet of the rider operating the pedals from touching thedrive sprocket 17 and thechain 19. - Next, a further explanation will be given, focusing on the transmission T.
- Referring to FIGS. 2 to 3, the transmission T includes: a
transmission case 20 with a chain type transmission mechanism M1 and a gear shift mechanism M2 for placing the transmission mechanism M1 into a desired position as described in gear shift operation. The transmission mechanism M1 and a derailleur 70 (stated later) as a component of the gear shift mechanism M2 are housed in thetransmission case 20. - The transmission mechanism M1 includes a one-way clutch 30 with a
ball spline 31 as a sliding mechanism. Adrive sprocket 32 is provided with atransmission sprocket cluster 40 consisting of a plurality oftransmission sprockets 41 to 47. An endless transmission chain C is provided with analignment guide 50 and a limitingmember 65. - In the
drive sprocket 32, a pair of circular syntheticresin side plates 32 b, that prevent disengagement of the chain C, is provided on both sides of theteeth 32 a to engage with the chain C. Since theside plates 32 b are made of synthetic resin, thedrive sprocket 32 is lightweight. - The
main shaft 12 a of thecrankshaft 12, which is rotated by the rider, is drivably connected with thedrive sprocket 32, located coaxially, through the one-way clutch 30. The one-way clutch 30 includes a clutch inner 30 a which consists of part of themain shaft 12 a, a clutch outer 30 b with a ratchet geared inner periphery and aclutch element 30 c which consists of a claw to engage with the ratchet gear, located between the clutch inner 30 a and the clutch outer 30 b. The one-way clutch 30 transmits the rotation of thecrankshaft 12 only in the normal rotation direction A (hereinafter, the normal rotation direction of various shafts and sprockets-upon normal rotation of thecrankshaft 12 is indicated by symbol A) to thedrive sprocket 32. - The
ball spline 31 is provided for enabling thedrive sprocket 32 to move in the direction of the rotational centerline L1 of themain shaft 12 a (which corresponds to the axial direction) and for rotating thedrive sprocket 32 together with the clutch outer 30 b of the one-way clutch 30 that is located between the one-way clutch 30 and thedrive sprocket 32. Theball spline 31 includes aninner cylinder 31 a which is integrally coupled with the clutch outer 30 b through a connectingpin 33 and rotatably supported on the outer periphery of themain shaft 12 a through abearing 34. Anouter cylinder 31 b is provided which is coaxial with theinner cylinder 31 a outwardly in the radial direction of theinner cylinder 31 a and is integrally coupled with thedrive sprocket 32. A plurality ofballs 31 c are located between theinner cylinder 31 a and theouter cylinder 31 b that are housed in a way to be able to roll across three pairs of housing grooves made in theinner cylinder 31 a and theouter cylinder 31 b, stretching parallel to the rotational centerline L1. Therefore, although theouter cylinder 31 b and thedrive sprocket 32 rotate together with theinner cylinder 31 a through theballs 31 c, they can move in the axial direction while theinner cylinder 31 a cannot move in the axial direction. - Lubricating oil reserved in the
transmission case 20 is used to lubricate parts of the transmission T which need lubrication such as the chain C,various sprockets crankshaft 12, one-way clutch 30,ball spline 31 and other sliding parts. For this reason, lubricating oil is reserved at the bottom of thetransmission case 20 so that thedrive sprocket 32's outer periphery including its teeth is below anoil surface 36. Drops of lubricating oil pumped up by thedrive sprocket 32 and the chain C and lubricant oil adhering to the chain C are supplied to various parts to be lubricated. - A plurality of transmission sprockets with different outside diameters (addendum circle diameters), seven
transmission sprockets 41 to 47 in this embodiment, are splined to theoutput shaft 15, which is rotatably supported by thetransmission case 20 through a pair ofbearings 35 held by thecases output shaft 15 and are coaxial with theoutput shaft 15. Therefore, the rotational centerline L3 of thetransmission sprockets 41 to 47 coincides with the rotational centerline L2 of theoutput shaft 15, which is parallel to the rotational centerline L1. All thetransmission sprockets 41 to 47 are axially arranged in the ascending order of speed and in the descending order of diameter, from the lowest speed 1-speed transmission sprocket 41 to the highest speed 7-speed transmission sprocket 47. - The chain C is wound between the
drive sprocket 32 and an active sprocket as onetransmission sprocket 41 to 47 which is selected from among thetransmission sprocket cluster 40 by the gear shift mechanism M2 (hereinafter called an “active sprocket”). Therefore, theoutput shaft 15 is rotated by thecrankshaft 12 at the gear ratio which is determined by the active sprocket drivably connected through the chain C with thedrive sprocket 32. - Referring to
FIG. 2 and FIGS. 6 to 9, analignment guide 50 is located between thedrive sprocket 32 and thetransmission sprocket cluster 40. More specifically, on the tight side of the chain C driven by the normally rotatingdrive sprocket 32, near the wind-in part of thedrive sprocket 32; when a stagnant part Cl, seeFIG. 9 , an extremely loose or folded part of the chain C, is generated as the tension of the tight side lowers, it prevents the stagnant part C1 from being caught in thedrive sprocket 32. - The
alignment guide 50 includes aguide part 52 which has a slightly larger axial width than the width of axial movement of the chain C as wound around eachtransmission sprocket 41 to 47 of thetransmission sprocket cluster 40 and forms analignment hole 51 through which the chain C in alignment passes. Alimiter 60 is provided which restrains the chain C as unwound from eachtransmission sprocket 41 to 47 from moving inward (inside the chain orbit). - The
guide part 52, which guides the stagnant part C1 of the chain C approaching thealignment guide 50 in a way to let it pass through thealignment hole 51 as aligned, is composed of anouter guide 53 as a first guide which is located outside the chain C (outside the chain orbit) with respect to thealignment hole 51 aninner guide 54 as a second guide which is located inside the chain C with respect to thealignment hole 51 and side guides 55 and 56 which are located on both sides of thealignment hole 51 in the axial direction. Theouter guide 53, which forms thealignment hole 51 in conjunction with theinner guide 54 and side guides 55 and 56, includes aguide roller 53 a as an inlet portion which lies near thetransmission sprocket cluster 40 and guides the chain C to thealignment hole 51 to form aninlet 51 a of thealignment hole 51 and anoutlet portion 53 b which lies near thedrive sprocket 32 to form anoutlet 51 b of thealignment hole 51. - The
outlet portion 53 b,inner guide 54,limiter 60 andleft side guide 55 are integrally built as a single first member, and theright side guide 56 is built as a second member. The first member and second member and theguide roller 53 a are made of self-lubricating or low friction synthetic resin. The first and second members are coupled with thefirst case 21 by means of a pair of bolts N3 passed through inner holes of a pair ofcollars 62 inserted into the members so that thealignment guide 50 is fixed on thetransmission case 20. Therefore, theside guide 56 is detachably coupled with the first member. Theguide roller 53 a is rotatably supported through abearing 57 b by asupport shaft 57 a both ends of which are supported by theside guide 55 andfirst case 21 on the left and by theside guide 56 andsecond case 22 on the right. - The
guide roller 53 a has an outercircumferential surface 58 as a first guide surface which guides the stagnant part C1 of the chain C so as to align it. The outercircumferential surface 58 has, in the axial direction, alarge diameter portion 58 a as a basic portion on the side of thetransmission sprocket 47 with the smallest outside diameter, and a small diameter portion, 58 b, 58 c, on the side of thetransmission sprocket 41 with the largest outside diameter which is more retreated outside the chain C than thelarge diameter portion 58 a. - The small diameter portion, 58 b, 58 c, which is smaller in diameter than the
large diameter portion 58 a, consists of: thesmallest diameter portion 58 c as the most retreated portion and a taperedportion 58 b as the transitional retreated portion which continuously retreats from thelarge diameter portion 58 a to thesmallest diameter portion 58 c. The diameter of the taperedportion 58 b continuously decreases from thelargest diameter portion 58 a to thesmallest diameter portion 58 c. - The
inner guide 54 has asecond guide surface 59 which guides the stagnant part C1 of the chain C so as to align it. Theguide surface 59 includes in the axial direction anusher portion 59 d which lies nearer to the chain C entry side than thealignment hole 51 and ushers the chain C into thealignment hole 51 and abasic portion 59 a located on the side of the smallest outsidediameter transmission sprocket 47 andprojection diameter transmission sprocket 41 projecting toward thesmall diameter portion large diameter portion 58 a andsmall diameter portion alignment hole 51 in conjunction with thelarge diameter portion 58 a andsmall diameter portion guide roller 53 a. Theprojection largest projection 59 c projecting toward thesmallest diameter portion 58 c and thetransitional projection 59 b projecting toward the taperedportion 58 b, which respectively correspond to thesmallest diameter portion 58 c and the taperedportion 58 b. - The
large diameter portion 58 a andbasic portion 59 a, the taperedportion 58 b andtransitional projection 59 b, and thesmallest diameter portion 58 c andlargest projection 59 c, which are opposite to each other, maintain the width D of thealignment hole 51 in the direction of inward or outward movement of the chain C upon shift of the chain C among thetransmission sprocket cluster 40 almost constant at any axial position. - Assuming that gear shift positions obtained by the
transmission sprocket cluster 40 are divided into two groups, low speed positions and high speed positions, when the chain C is not stagnant, the chain C as wound around thetransmission sprockets transmission sprocket 43 as active sprockets at low speed positions (namely low speed transmission sprockets) respectively for contacting thesmallest diameter portion 58 c and taperedportion 58 b of theguide roller 53 a to give a slight tension (part of the chain C wound around thetransmission sprocket 41 is indicated by two-dot chain line inFIG. 6 ), and the chain C as wound around thetransmission sprockets 44 to 47 as active sprockets at high speed positions (namely high speed transmission sprockets) contacts thebasic portion 59 a of theinner guide 54 to give a slight tension (art of the chain C wound around thetransmission sprocket 47 is indicated by solid line inFIG. 6 ) so as to prevent the chain C from loosening on its tight side. - When the chain C is not stagnant, the chain C as wound around the
transmission sprockets transmission sprocket 43 does not touch thelargest projection 59 c and thetransitional projection 59 b of theinner guide 54 respectively, and the chain C as wound around thetransmission sprockets 44 to 47 does not contact thelarge diameter portion 58 a of theguide roller 53 a. - On the other hand, when the chain C is stagnant, as typically illustrated in
FIG. 9 , the chain C as wound around thetransmission sprockets transmission sprocket 43 and around thetransmission sprockets 44 to 47, respectively, contacts thesmallest diameter portion 58 c, taperedportion 58 b andlarge diameter portion 58 a of theguide surface 58 of theguide roller 53 a and contacts theusher portion 59 d,largest projection 59 c,transitional projection 59 b andbasic portion 59 a of theguide surface 59 of theinner guide 54 and guides the stagnant part Cl so as to let the chain C pass through thealignment hole 51 as aligned. - The
limiter 60, which is located in a position to overlap thetransmission sprockets 41 to 47 when viewed sideways, extends from theinner guide 54 toward thetransmission sprockets 41 to 47 and has atip 60 a in which asmany grooves 60 b, through which the teeth of thetransmission sprockets 41 to 47 pass individually, as thetransmission sprockets 41 to 47 are formed. - Therefore, when the bicycle B severely moves up and down in a short time, for example, because of a rough road surface, even if vertical vibration on the tight side of the chain C or inward or outward vibration of the chain C (hereinafter “inward/outward”) occurs, it touches the
outer guide 53 and theinner guide 54, which limits the amplitude of vibration and thus suppresses vibration of the chain C and allows the chain C to pass through thealignment hole 51 as aligned, thereby permitting a smooth operation of the chain C. - In an operating condition of the bicycle B in which the chain C has a stagnant part C1 due to a tension decrease on the tight side of the chain C, for instance, when the bicycle B is freewheeling forward with the
crankshaft 12 at a stop or rotating in the reverse direction, thedrive sprocket 32 is rotated in the normal rotational direction A through the chain C by the torque transmitted from the rear wheel Wr to thetransmission sprocket cluster 40 through the driving power transmission mechanism and theoutput shaft 15. At this moment, it may happen that the tension of the tight side of the chain C declines and a stagnant part C1 is generated on the tight side; especially when the bicycle B moves forward in a condition wherein thecrankshaft 12 suddenly stops or rotates in the reverse direction after its normal rotation, it may happen that the chain C loosens considerably and a folded stagnant part C1 is generated on the wind-in side of thedrive sprocket 32. In such a case, without thealignment guide 50, the stagnant part C1 might be caught in thedrive sprocket 32. - However, even if a stagnant part C1 is generated on the tight side, due to the presence of the
alignment guide 50 the stagnant part C1 contacts theouter guide 53 and theinner guider 54 and is thus guided in a way to be aligned, so that the chain C passes through thealignment hole 51 as aligned and operates smoothly. - Referring to FIGS. 1 to 4, the gear shift mechanism M2 includes a gear
shift operation mechanism 70, and aderailleur 80 as a shift mechanism which shifts the chain C from one sprocket to another among thetransmission sprocket cluster 40 as described in a gear shift operation by the gearshift operation mechanism 70. The chain C is put around thedrive sprocket 32, an active sprocket and aguide pulley 82 and atension pulley 92, both located on the loose side of the chain C which is driven by normal rotation of thecrankshaft 12. - The gear
shift operation mechanism 70, which is connected with thederailleur 80 in thetransmission case 20, includes a gearshift operation member 71, seeFIG. 1 , such as a shift lever to be operated by the rider and anoperational cable 72 as an operational power transmission member which connects the gearshift operation member 71 with thederailleur 80 to transmit the operation of the gearshift operation member 71 to thederailleur 70. - The
operational cable 72 includes anouter cable 72 a in the form of a flexible tube held by the body frame F and a flexibleinner cable 72 b inserted into theouter cable 72 a. Theinner cable 72 b is coupled with the gearshift operation member 71 at its bottom and with thederailleur 80 at its top. - When the
operational cable 72 is mounted in thetransmission case 20, before inserting theoperational cable 72 in agrommet 74 fitted to thefirst case 21, the portion of theoperational cable 72 near its top is inserted into acylindrical insertion tube 73 latched to aretainer 81 a with a recess, provided at thebase 81 of thederailleur 80 so that theoperational cable 72 and theinsertion tube 73 are joined together. In this condition, theouter cable 72 a inserted from oneend 73 a of theinsertion tube 73 is latched to theinsertion tube 73, and theinner cable 72 b inserted into theouter cable 72 a through a hole at theother end 73 b of theinsertion tube 73 extends outside theinsertion tube 73. Then, theinsertion tube 73 with theoperation cable 72 inserted therein is inserted in thegrommet 74 from outside thefirst case 21 and held by theretainer 81 a. At this time, theinner cable 72 b is passed through a hole at the bottom of theretainer 81 a before an engaging part at its tip is latched to alink 83 b of aparallel link mechanism 83. Since theoperation cable 72 passed through thetransmission case 20 and held by theretainer 81 a, as integral with theinsertion tube 73, is thus inserted in thegrommet 74 fitted to thetransmission case 20 together with theinsertion tube 73, it is easy to fit theoperation cable 72 to thederailleur 80. - Referring to FIGS. 2 to 3, the
derailleur 80 located above themain shaft 12 a of thecrankshaft 12 includes acylindrical base 81 molded integrally with theretainer 81 a which is fixed and held on thecases outer cable 72 a, aguide pulley 82 which, when shifting the chain C among thetransmission sprockets 41 to 47, guides the chain C in a way to wind it around an active sprocket, a holder H which rotatably supports theguide pulley 82, aparallel link mechanism 83 having a pair oflinks pulley 82 in the axial direction and the radial direction of the rotational centerline L3 as described in gear shift operation by the gearshift operation mechanism 70 and atensioner 84 for adjusting the tension of the chain C. - The holder H includes a
first holder part 86 and asecond holder part 87 which are located on both sides, in the axial direction, of theguide pulley 82 having a rotational centerline L4 parallel to the rotational centerline L3, or on the left and right, respectively, and coupled by a pair ofrivets support part 88 which rotatably supports theguide pulley 82. Thesupport part 88 swingably supports a pair of arms, afirst arm part 95 and asecond arm part 96, which will be described later. - The
second holder part 87 includes acoupling part 87 a which is located outwardly in the radial direction of theguide pulley 82 and is pivotally coupled with the pair oflinks parallel link mechanism 83. Aspring housing 87 b is provided which is located on the right of theguide pulley 82 and houses atension spring 93. Thelinks support shafts 91 provided at thebase 81, and as they are operated through theinner cable 72 b latched to thecoupling part 83 b 1 of thelink 83 b, they swing around a pair of swing centerlines defined by thesupport shafts 91 and guide theguide pulley 82 along a cluster of addendum circles consisting of the addendum circles of thetransmission sprockets 41 to 47. - Referring to
FIGS. 2, 3 and 6, the limitingmember 65, which receives the chain C disengaged from theguide pulley 82 to limit the disengagement, is located between theguide pulley 82 and an active sprocket, on the wind-out side of theguide pulley 82 rotating in the normal rotational direction A (on the wind-in side of theguide pulley 82 rotating in the reverse direction), outward from a tangent line common to the addendum circle of theguide pulley 82 and the addendum circle of the active sprocket in the radial direction of theguide pulley 82 when viewed sideways.FIGS. 2 and 6 illustrate an example of a disengaged part C2 of the chain C by two-dot chain lines. This kind of disengagement of the chain C from theguide pulley 82 occurs when thetransmission sprockets 41 to 47 are not rotating normally. More specifically, when the bicycle B is operating backward, namely thetransmission sprocket 41 to 47 is rotating in the reverse direction or when the bicycle is stationary, namely thetransmission sprockets 41 to 47 are stationary. - The limiting
member 65 lies between the rotational centerline L1 of thecrankshaft 12 and the rotational centerline L3 of thetransmission sprockets 41 to 47, in a position to cross a plane P including the rotational centerlines L1 and L3 and overlap thetransmission sprockets 41 to 47 when viewed sideways, and molded integrally with the above first member of thealignment guide 50, projecting from thelimiter 60 toward theguide pulley 82. The limitingmember 65 uses thealignment guide 50 and is separate from the holder H supporting theguide pulley 82. - Referring to
FIG. 8 as well, the limitingmember 65 has arecess 66 and takes the form of a box reinforced by arib 67 and is lightweight. Thecontact part 68 for contacting the disengaged chain C consists of a flat wall having a contact surface which is nearer to theguide pulley 82 than to the plane P and parallel to the plane P and stretches across the axial movement area of the chain C wound aroundplural transmission sprockets 43 to 47. - Referring to
FIGS. 2, 3 and 10, thetensioner 84 includes atension pulley 92 which presses the chain C between thedrive sprocket 32 and theguide pulley 82 to give tension to the chain C, an arm R which is located between the first andsecond holder parts retainer 88 of the holder H and rotatably supports thetension pulley 92 and atension spring 93. - The
tension pulley 92 has an outercircumferential surface 94 as a part to contact the chain C. The outercircumferential surface 94 consists of an axially parallel plane so that in a gear shift operation by thederailleur 80, when thetension pulley 92 moves axially together with theguide pulley 82, it constitutes a surface which allows the chain C to slide axially, due to a torsion in the chain C which occurs because thetension pulley 92 moves before the axial movement of thedrive sprocket 32 following the axial movement of thetension pulley 92, and a link Ca of the chain C contacts the outercircumferential surface 94 at an outer border Ca1 inside it. - The outer
circumferential surface 94, which almost fits the outer border Ca1 in the circumferential direction (or when viewed sideways), consists of a curved surface having aconvex part 94 a which matches a concave part of the outer border Ca1. This suppresses slippage of the chain C on the outer circumferential surface in the operating direction. - The arm R consists of a pair of arm parts, a first arm part and a
second arm part tension pulley 92 or left and right in the axial direction, respectively, and located between the first andsecond holder parts support part 97 which rotatably supports thetension pulley 92. Thesupport part 97 consists of abolt 97 a as a coupling means to couple the first andsecond arm parts tension pulley 97 to be attached to, and detached from, thearm parts bearing 97 b fitted onto thebolt 97 a to support thetension pulley 92. Thebolt 97 a has a groove to house a retainingring 97 d which prevents loosening of a nut 97C screwed on thebolt 97 a. - Taking advantage of the fact that the
tension pulley 92 can be attached to, and detached from, the arm R, this embodiment uses an endless chain C. More specifically, the endless chain C is wound around thedrive sprocket 32,transmission sprocket 41 to 47 and guidepulley 82 with thebolt 97 a removed, thetension pulley 92 removed from the arm R and theside guide 56 and theside guide 56 of thealignment guide 50 as the second member, seeFIG. 7 , removed. After that, thetension pulley 92 is attached to the arm R with thebolt 97 a from inside the chain C and in thealignment guide 50, the first member is attached to the second member. This process, in which the endless chain C is wound around the sprockets, eliminates the need for a step of connecting both chain ends which a chain having ends would require. In addition, the difference in the coupling force between links Ca is reduced. - The
tension spring 93, composed of two torsion coil springs with different diameters, biases the arm R and thetension pulley 92 around the rotational centerline L4 clockwise as seen inFIG. 2 by its resilience to push the tension pulley C against the chain C. - Referring to
FIG. 7 andFIG. 4 (a),soundproof sheets transmission sprockets 41 to 47 which is generated when shifting the chain C to another sprocket, are attached at positions of the first andsecond cases transmission sprocket cluster 40 and theguide pulley 82 when viewed sideways. Thesesoundproof sheets transmission case 20. Referring toFIG. 1 , the above collision noise transmitted to the hollow main frame 2 and noise of flying pebbles hitting the main frame 2 are effectively attenuated by asoundproof sheet 102 attached to the left and right sides of the front part, a wide area of the main frame 2. - Next, the functions and effects of the abovementioned embodiment will be explained.
- When the rider drives the
crankshaft 12 in the normal rotational direction A, or when the bicycle B operates forward while thecrankshaft 12 rotates in the reverse direction or is at a stop, upon the operation of the gearshift operation member 71, thederailleur 80, arm R andtension pulley 92 are placed in their basic 7-speed position as indicated by solid lines in FIGS. 2 to 4(a) and thetransmission sprocket 47 is selected as an active sprocket from among thetransmission sprocket cluster 40, and the chain C is placed around thedrive sprocket 32 and thetransmission sprocket 47 in their positions as indicated by solid lines inFIGS. 3 and 4 (a). Thecrankshaft 12, which rotates in the normal rotation direction A as the rider works thepedals 13, rotates thedrive sprocket 32 through the one-way clutch 30, and thedrive sprocket 32 rotates thetransmission sprocket 47,output shaft 15 and drivesprocket 17 through the chain C at a gear ratio determined by thesprockets drive sprocket 17 rotates the drivensprocket 18 and rear wheel Wr through thechain 19. - When the gear shift
operational member 71 is operated to select as an active sprocket, for example, thetransmission sprocket 41, among lowerspeed transmission sprockets 41 to 46 for gear shift from the 7-speed position to another position, theinner cable 72 b activates theparallel link mechanism 83 of thederailleur 80 and theparallel link mechanism 83 moves the holder H, guidepulley 82, arm R andtension pulley 92 to the left in the axial direction and outwardly in the radial direction with respect to the rotational centerline L3 and brings them into the 1-speed position as indicated by two-dot chain lines in FIGS. 2 to 4(a). Then, the chain C, which moves to the left together with theguide pulley 82 and thetension pulley 92, moves thedrive sprocket 32 to the left in the axial direction of themain shaft 12 a of thecrankshaft 12 and brings thedrive sprocket 32 into the position as indicated by two-dot chain lines inFIGS. 3 and 4 (a). At this time, the chain C is put around thetransmission sprocket 41 and drivably coupled with thedrive sprocket 32 through the chain C. - When the gear
shift operation member 71 is operated to select a higherspeed transmission sprocket 42 to 47 for a gear shift from this 1-speed position, theinner cable 72 b activates theparallel link mechanism 83 of thederailleur 80 and theparallel link mechanism 83 moves the holder H, guidepulley 82, arm R andtension pulley 92 to the right in the axial direction and inward in the radial direction with respect to the rotational centerline L3. Thereafter; the chain C, which moves to the right together with theguide pulley 82 and thetension pulley 92, moves thedrive sprocket 32 to the right with respect to themain shaft 12 a and at the same time, the chain C is wound around the selectedtransmission sprocket 42 to 47. - As mentioned above, the
derailleur 80, which is activated as described in a gear shift operation by the gearshift operation mechanism 70, shifts the chain C among thetransmission sprockets 41 to 47, so that the bicycle B operates at a gear ratio determined by a selected active sprocket around which the chain C is wound, and thedrive sprocket 32. - In this transmission T, the
alignment guide 50 consists of theguide roller 53 a having an outercircumferential surface 58 which guides a stagnant part C1 of the chain C so as to align it and the outercircumferential surface 58 has, in the axial direction, alarge diameter portion 58 a on the side of thetransmission sprocket 47 with the smallest outside diameter, and asmallest diameter portion 58 c on the side of thetransmission sprocket 41 with the largest outside diameter and a taperedportion 58 b, which are more retreated outside the chain C than thelarge diameter portion 58 a and the chain C, which is wound around atransmission sprocket 41 to 43 while it is not stagnant, contacts thesmallest diameter portion 58 c and the taperedportion 58 b. Consequently, the stagnant part C1 of the chain C is guided by theguide roller 53 a of thealignment guide 50 to reach thealignment hole 51 as aligned, resolving the stagnancy and preventing the stagnant part C1 from being caught in thedrive sprocket 32 without resolving the stagnancy C1. In addition, since the chain C, which contacts theguide roller 53 a while it is not stagnant, contacts thesmallest diameter portion 58 c and taperedportion 58 b of theguide roller 53 a, the chain C curves less than when it contacts thelarge diameter portion 58 a without thesmallest diameter portion 58 c and the taperedportion 58 b and the friction applied from theguide roller 53 a to the chain C is thus reduced and the operating performance of the chain C is improved. - The
guide roller 53 a constitutes a guide part of thealignment guide 50, and the chain C, which is wound around thetransmission sprocket transmission sprocket 43 while the chain C is not stagnant, contacts thesmallest diameter portion 58 c and the taperedportion 58 b which constitute thesmall diameter portion guide roller 53 a further smoothens the guidance to align the stagnant part C1 and accelerates resolution of the stagnant part C1. In addition, the friction applied from thesmall diameter portion speed transmission sprocket 41 to 43 while the chain C is not stagnant is reduced so that the operating performance of the bicycle B at a low speed gear position is improved. - Since the
guide surface 59 of theinner guide 52 of thealignment guide 50 has thelargest projection 59 c and thetransitional projection 59 b projecting toward thesmallest diameter portion 58 c and the taperedportion 58 b, in order to maintain the width D of thealignment hole 51 in the direction of outward or inward movement of the chain C almost constant at any axial position, due to theprojections alignment hole 51 with the presence of thesmallest diameter portion 58 c and taperedportion 58 b is almost equal to the width D of thealignment hole 51 defined by thelarge diameter portion 58 a and thebasic portion 59 a, a portion other than theprojections guide surface 59. Therefore, alignment properly takes place in thesmallest diameter portion 58 c and taperedportion 58 b. As a consequence, the friction from theguide roller 53 a is reduced and proper alignment by thealignment guide 50 is ensured. - Since the limiting
member 65, which restricts disengagement of the chain C from theguide pulley 82, is located between theguide pulley 82 and an active sprocket, on the wind-out side of theguide pulley 82 rotating in the normal rotation direction A, outwardly from a tangent line common to theguide pulley 82 and the active sprocket in the radial direction of theguide pulley 82, if a torsion occurs in the chain C due to a large axial movement of the guide pulley upon a gear shift operation when thetransmission sprockets 41 to 47 are not rotating normally, more specifically when the bicycle B is being operated backward, namely thetransmission sprockets 41 to 47 are rotating in the reverse direction or when the bicycle is stationary or thetransmission sprockets 41 to 47 are at a stop, the friction between links of the chain C increases. If, because of the torsion, it becomes difficult for the chain C to sag along theguide pulley 82 and the chain C disengages from theguide pulley 82, the limitingmember 65 contacts the chain C to alleviate the degree of disengagement of the chain C so that the operating performance of the chain C on theguide pulley 82 is improved. - Since the limiting
member 65 lies between the rotational centerline L1 and the rotational centerline L3, in a position to overlap thetransmission sprockets 41 to 47 when viewed sideways and is located in the space between the rotational centerlines L1 and L2, the distance between thecrankshaft 12 and thetransmission sprockets 41 to 47 need not be increased due to the presence of the limitingmember 65. As a consequence, it is possible to provide the limitingmember 65 while keeping the compactness of the transmission 1 - Since the limiting
member 65 is molded integrally with thealignment guide 50, the transmission T provided with the limitingmember 65 is obtained without an increase in the number of components. Since the limitingmember 65 uses thealignment guide 50 and is separate from the holder H supporting theguide pulley 82, the member which moves axially together with theguide pulley 82 upon gear shift operation is lighter than when the limitingmember 65 is integral with the holder H, which allows quicker movement of theguide pulley 82 and improves the gear shift operability, namely the ease and reliability of gear shift. - Since the outer
circumferential surface 94 of thetension pulley 92, which is to contact the chain C, consists of a surface which enables the chain C to slide axially and the chain C axially moves across an extensive area in the circumferential direction of thetension pulley 92 during axial movement of thetension pulley 92 upon a gear shift operation, the torsion in the chain C decreases and the friction between links Ca of the chain C decreases as well. Therefore, the chain C is easy to sag along the outercircumferential surface 94 of thetension pulley 92. Consequently, the chain C smoothly operates on thetension pulley 92 and the operating performance of the chain C is improved. In addition, since the operating performance of the chain C that operates toward theguide pulley 82 is improved, the gear shift operability is improved. - Since the
transmission case 20 is located between the front wheel Wf and rear wheel Wr of the bicycle B and in the transmission T, located in the center of the bicycle B, thedrive sprocket 32 and thetransmission sprocket cluster 40 are adjacent to each other, the torsion in the chain C which occurs upon a gear shift operation tends to be considerable. However, thetension pulley 92 substantially reduces the torsion and therefore the chain C smoothly operates on thetension pulley 92. As a consequence, the operating performance of the chain C is improved in the transmission T located in the center of the bicycle B. - A partially modified version of the abovementioned embodiment is explained below, focusing on modifications.
- The first guide may be not be a roller but may be a member that cannot rotate. The second guide may consist of a roller. The retreated portion may be provided in the inner guide and located inside the chain C.
- The limiting member may prevent the chain C from disengaging from the guide pulley.
- The invention being thus described, it will be obvious that the same may be varied in many ways. Such variations are not to be regarded as a departure from the spirit and scope of the invention, and all such modifications as would be obvious to one skilled in the art are intended to be included within the scope of the following claims.
Claims (20)
1. A bicycle transmission comprising:
a drive sprocket rotated by a crankshaft;
a transmission sprocket cluster disposed in the axial direction and composed of a plurality of transmission sprockets having distinct outside diameters;
a chain wound around the drive sprocket and the transmission sprockets; and
a shift mechanism for shifting the chain among the transmission sprocket cluster according to a gear shift operation; and
an alignment guide being located between the drive sprocket and the transmission sprocket cluster to align a stagnant part of the chain;
wherein the alignment guide consists of a guide part with a guide surface for guiding the stagnant part of the chain in a way to align the chain;
the guide surface, in the axial direction, being provided with a basic portion located on the side of the transmission sprocket with the smallest outside diameter, and a retreated portion which is located on the side of the transmission sprocket with the largest outside diameter and more retreated inside or outside the chain than the basic portion; and
the chain contacts the retreated portion while the chain is not stagnant.
2. The bicycle transmission according to claim 1 , wherein the guide part is a guide roller having an outer circumferential surface which constitutes the guide surface and the retreated portion is a small diameter portion with a diameter smaller than the basic portion and the chain wound around the transmission sprocket with the largest outside diameter contacts the small diameter portion while the chain is not stagnant.
3. The bicycle transmission according to claim 1 , wherein the alignment guide includes a first guide as the guide part and a second guide having a second guide surface for forming an alignment hole through which the chain passes, in conjunction with a first guide surface as the guide surface of the first guide; and
the second guide surface has a projection projecting toward the retreated portion in order to maintain the width of the alignment hole in the direction of inward or outward movement of the chain almost constant at any axial position.
4. The bicycle transmission according to claim 2 , wherein the alignment guide includes a first guide as the guide part and a second guide having a second guide surface for forming an alignment hole through which the chain passes, in conjunction with a first guide surface as the guide surface of the first guide; and
the second guide surface has a projection projecting toward the retreated portion in order to maintain the width of the alignment hole in the direction of inward or outward movement of the chain almost constant at any axial position.
5. The bicycle transmission according to claim 1 , and further including side guides formed on each side of the alignment guide.
6. The bicycle transmission according to claim 5 , wherein a limiter and a first side guide are integrally formed relative to each other and positioned on a first side of said alignment guide and the second side guide is displaced relative thereto and is positioned on a second side of said alignment guide.
7. The bicycle transmission according to claim 6 , wherein the second side is secured to a transmission case wherein the alignment guide is fixed to the transmission case.
8. The bicycle transmission according to claim 2 , wherein the guide roller is tapered from small diameter portion to the largest outside diameter portion to accommodate said chain as it is shifted from a largest transmission sprocket to a smallest transmission sprocket.
9. A bicycle transmission comprising:
a drive sprocket rotated by a crankshaft;
a transmission sprocket cluster including a plurality of transmission sprockets disposed in the axial direction; and
a shift mechanism for shifting the chain among the transmission sprocket cluster according to a gear shift operation;
said shift mechanism including a guide pulley around which the chain is wound, said guide pulley being moving axially for guiding the chain wound around one active sprocket selected from among the transmission sprocket cluster; and
a limiting member for the bicycle transmission, said limiting member restricting disengagement of the chain from the guide pulley;
said limiting member being located between the guide pulley and the active sprocket, outward in the radial direction of the guide pulley.
10. The bicycle transmission according to claim 9 , wherein the limiting member is located between a rotational centerline of the crankshaft and a rotational centerline of the transmission sprockets in a position to overlap the transmission sprockets when viewed sideways.
11. The bicycle transmission according to claim 10 , and further including an alignment guide located between the drive sprocket and the transmission sprocket cluster for aligning a stagnant part of the chain, said limiting member being molded integrally with the alignment guide.
12. The bicycle transmission according to claim 9 , wherein said limiter is positioned to overlap the transmission sprocket and extends from an inner guide towards the transmission sprocket.
13. The bicycle transmission according to claim 12 , wherein said limiter includes a tip having as many grooves as teeth of the transmission sprocket to pass individually.
14. The bicycle transmission according to claim 12 , wherein said limiter suppresses vibration of the chain while allowing the chain to pass through an alignment hole to permit smooth operation of the chain.
15. A bicycle transmission comprising:
a drive sprocket rotated by a crankshaft;
a transmission sprocket cluster including a plurality of transmission sprockets disposed in the axial direction; and
a shift mechanism for shifting the chain among the transmission sprocket cluster according to gear shift operation;
said shift mechanism includes a guide pulley around which the chain is wound and a tension pulley for tensioning the chain;
said guide pulley moving axially together with the tension pulley upon a gear shift operation for guiding the chain wound around one active sprocket selected from among the transmission sprocket cluster; and
a part of the tension pulley to contact the chain consists of a surface on which the chain can slide axially.
16. The bicycle transmission according to claim 15 , and further including a transmission case for supporting the crankshaft and the transmission sprocket cluster, said transmission case being located between the front wheel and rear wheel of the bicycle
17. The bicycle transmission according to claim 15 , and further including a first arm located on one side of the tension pulley and a second arm located on a second side of the tension pulley and a support part for rotatably supporting the tension pulley relative to the first and second arms.
18. The bicycle transmission according to claim 17 , wherein said support part is a bolt for securing the first and second arms relative to each other and further including a bearing for rotatably supporting the tension pulley relative to the bolt.
19. The bicycle transmission according to claim 15 , and further including a tension spring for biasing the first and second arms in a clockwise direction.
20. The bicycle transmission according to claim 15 , and further including soundproof sheets for attenuating noise of collision between the chain and the transmission sprockets.
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
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JP2005118931A JP4601480B2 (en) | 2005-04-15 | 2005-04-15 | Bicycle transmission |
JP2005-118931 | 2005-04-15 |
Publications (1)
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US20060240919A1 true US20060240919A1 (en) | 2006-10-26 |
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Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
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US11/403,967 Abandoned US20060240919A1 (en) | 2005-04-15 | 2006-04-14 | Bicycle transmission |
Country Status (5)
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US (1) | US20060240919A1 (en) |
JP (1) | JP4601480B2 (en) |
CN (1) | CN1847082B (en) |
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TW (1) | TWI290115B (en) |
Cited By (11)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US20040192480A1 (en) * | 2003-03-26 | 2004-09-30 | Honda Motor Co., Ltd. | Transmission apparatus for a bicycle |
US20110028252A1 (en) * | 2009-07-31 | 2011-02-03 | Tzvetan Nedialkov Tzvetkov | Universal skip-free derailleur |
US20110256971A1 (en) * | 2010-04-14 | 2011-10-20 | Kilshaw Richard J | Chain Tensioner |
US20160257375A1 (en) * | 2015-03-06 | 2016-09-08 | Shimano Inc. | Bicycle transmission apparatus |
US20160257373A1 (en) * | 2015-03-06 | 2016-09-08 | Shimano Inc. | Bicycle transmission apparatus |
US20170274961A1 (en) * | 2016-02-29 | 2017-09-28 | Shimano Inc. | Bicycle Chain Device |
US10066673B2 (en) * | 2015-12-14 | 2018-09-04 | Shimano Inn. | Bicycle crank assembly |
US10316951B2 (en) | 2016-07-13 | 2019-06-11 | Shimano Inc. | Bicycle drive unit |
US10435112B2 (en) * | 2017-04-07 | 2019-10-08 | Shimano Inc. | Bicycle drive train |
US20210276663A1 (en) * | 2020-03-03 | 2021-09-09 | William W. Nelson | Kits to convert single-speed bicycles to multi-speed bicycles |
US20230264781A1 (en) * | 2022-02-18 | 2023-08-24 | Joseph Francis Keenan | System and method for bicycle transmission |
Families Citing this family (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP5891361B2 (en) * | 2011-06-01 | 2016-03-23 | パナソニックIpマネジメント株式会社 | Electric bicycle drive device and electric bicycle |
KR101665789B1 (en) * | 2014-12-12 | 2016-10-12 | 두산중공업 주식회사 | Apparatus for arranging chain of bicycle |
JP6605847B2 (en) * | 2015-06-05 | 2019-11-13 | ライフロボティクス株式会社 | Robot arm mechanism |
Citations (12)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US3398973A (en) * | 1966-06-15 | 1968-08-27 | Shimano Industrial Co | Driving chain tensioning device in a bicycle equipped with coaster brake and exposedspeed change mechanism |
US3402942A (en) * | 1966-06-17 | 1968-09-24 | Shimano Industrial Co | Device for tensioning the driving chain in a bicycle equipped with coaster brake and exposed speed change gear |
US3785219A (en) * | 1972-06-05 | 1974-01-15 | J Anthamatten | Coaster brake system for a multi-speed bicycle |
US4306871A (en) * | 1978-12-30 | 1981-12-22 | Shimano Industrial Company, Limited | Rear derailleur and control wire guide |
US4734323A (en) * | 1986-04-22 | 1988-03-29 | Toyoda Gosei Co., Ltd. | Vibration damping soundproof sheets for use in vehicles |
US4842569A (en) * | 1987-11-16 | 1989-06-27 | Recreational Accessoried Corporation | Bicycle transmission having infinitely variable drive ratio |
US5460576A (en) * | 1993-10-07 | 1995-10-24 | Barnett; Robert L. | Bicycle chain guide |
US5553510A (en) * | 1995-02-27 | 1996-09-10 | Balhorn; Alan C. | Multi-speed transmission |
US5725450A (en) * | 1996-08-21 | 1998-03-10 | Joshua Paris | Device for preventing derailment of a bicycle chain |
US6287228B1 (en) * | 1999-11-12 | 2001-09-11 | Shimano, Inc. | Rear derailleur with cable guide roller |
US20040009835A1 (en) * | 2002-03-20 | 2004-01-15 | Jon Heim | Multiple sprocket, multiple function chain guide |
US20040014543A1 (en) * | 2000-07-21 | 2004-01-22 | Van Der Linde Freddy | Gear for a bicycle |
Family Cites Families (12)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
FR2370624A1 (en) * | 1976-11-10 | 1978-06-09 | Houze Michel | Motorcycle with weight transfer compensation - has axis of swing arms arranged higher than upper run of drive chain and anti-dive brake |
JPS5633830Y2 (en) * | 1977-06-14 | 1981-08-10 | ||
JPS5632391Y2 (en) * | 1978-07-11 | 1981-08-01 | ||
JPS55178491U (en) * | 1979-06-08 | 1980-12-22 | ||
JPS6029791U (en) * | 1983-08-04 | 1985-02-28 | 株式会社シマノ | bicycle rear derailleur |
DE4129198A1 (en) * | 1991-09-03 | 1993-03-04 | Heinz Mueller | Derailleur gearchange for bicycle - has sprockets on rear block moved to change gear, instead of chain |
JP2541980Y2 (en) * | 1992-05-29 | 1997-07-23 | 宮田工業株式会社 | Chain entrainment prevention plate for bicycles |
US5873590A (en) * | 1996-02-19 | 1999-02-23 | Exedy Corporation | Bicycle |
AT406365B (en) * | 1997-02-21 | 2000-04-25 | Josef Prajczer | BICYCLE GEAR |
DE10082555B4 (en) * | 1999-09-01 | 2007-11-08 | Nicolai, Karlheinz, Dipl.-Ing. (TU) | Bicycle with rear swingarm |
JP4115166B2 (en) * | 2002-05-31 | 2008-07-09 | 本田技研工業株式会社 | Bicycle with continuously variable transmission |
JP4115311B2 (en) * | 2003-03-26 | 2008-07-09 | 本田技研工業株式会社 | Bicycle transmission |
-
2005
- 2005-04-15 JP JP2005118931A patent/JP4601480B2/en not_active Expired - Fee Related
-
2006
- 2006-03-15 NL NL1031375A patent/NL1031375C2/en not_active IP Right Cessation
- 2006-03-17 TW TW095109194A patent/TWI290115B/en not_active IP Right Cessation
- 2006-04-14 US US11/403,967 patent/US20060240919A1/en not_active Abandoned
- 2006-04-14 CN CN2006100754146A patent/CN1847082B/en not_active Expired - Fee Related
Patent Citations (13)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US3398973A (en) * | 1966-06-15 | 1968-08-27 | Shimano Industrial Co | Driving chain tensioning device in a bicycle equipped with coaster brake and exposedspeed change mechanism |
US3402942A (en) * | 1966-06-17 | 1968-09-24 | Shimano Industrial Co | Device for tensioning the driving chain in a bicycle equipped with coaster brake and exposed speed change gear |
US3785219A (en) * | 1972-06-05 | 1974-01-15 | J Anthamatten | Coaster brake system for a multi-speed bicycle |
US4306871A (en) * | 1978-12-30 | 1981-12-22 | Shimano Industrial Company, Limited | Rear derailleur and control wire guide |
US4734323A (en) * | 1986-04-22 | 1988-03-29 | Toyoda Gosei Co., Ltd. | Vibration damping soundproof sheets for use in vehicles |
US4842569A (en) * | 1987-11-16 | 1989-06-27 | Recreational Accessoried Corporation | Bicycle transmission having infinitely variable drive ratio |
US5460576A (en) * | 1993-10-07 | 1995-10-24 | Barnett; Robert L. | Bicycle chain guide |
US5553510A (en) * | 1995-02-27 | 1996-09-10 | Balhorn; Alan C. | Multi-speed transmission |
US5725450A (en) * | 1996-08-21 | 1998-03-10 | Joshua Paris | Device for preventing derailment of a bicycle chain |
US6287228B1 (en) * | 1999-11-12 | 2001-09-11 | Shimano, Inc. | Rear derailleur with cable guide roller |
US20040014543A1 (en) * | 2000-07-21 | 2004-01-22 | Van Der Linde Freddy | Gear for a bicycle |
US20040009835A1 (en) * | 2002-03-20 | 2004-01-15 | Jon Heim | Multiple sprocket, multiple function chain guide |
US7059983B2 (en) * | 2002-03-20 | 2006-06-13 | Jon Heim | Multiple sprocket, multiple function chain guide |
Cited By (19)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US20040192480A1 (en) * | 2003-03-26 | 2004-09-30 | Honda Motor Co., Ltd. | Transmission apparatus for a bicycle |
US7381143B2 (en) * | 2003-03-26 | 2008-06-03 | Honda Motor Co., Ltd. | Transmission apparatus for a bicycle |
US20110028252A1 (en) * | 2009-07-31 | 2011-02-03 | Tzvetan Nedialkov Tzvetkov | Universal skip-free derailleur |
US20110256971A1 (en) * | 2010-04-14 | 2011-10-20 | Kilshaw Richard J | Chain Tensioner |
US8944945B2 (en) * | 2010-04-14 | 2015-02-03 | Richard J. Kilshaw | Chain tensioner |
TWI669242B (en) * | 2015-03-06 | 2019-08-21 | 日商島野股份有限公司 | Bicycle transmission apparatus |
US20160257375A1 (en) * | 2015-03-06 | 2016-09-08 | Shimano Inc. | Bicycle transmission apparatus |
US9623931B2 (en) * | 2015-03-06 | 2017-04-18 | Shimano Inc. | Bicycle transmission apparatus |
US20160257373A1 (en) * | 2015-03-06 | 2016-09-08 | Shimano Inc. | Bicycle transmission apparatus |
US9789928B2 (en) * | 2015-03-06 | 2017-10-17 | Shimano Inc. | Bicycle transmission apparatus |
US10066673B2 (en) * | 2015-12-14 | 2018-09-04 | Shimano Inn. | Bicycle crank assembly |
US20170274961A1 (en) * | 2016-02-29 | 2017-09-28 | Shimano Inc. | Bicycle Chain Device |
US10589821B2 (en) * | 2016-02-29 | 2020-03-17 | Shimano Inc. | Bicycle chain device |
US10316951B2 (en) | 2016-07-13 | 2019-06-11 | Shimano Inc. | Bicycle drive unit |
US10435112B2 (en) * | 2017-04-07 | 2019-10-08 | Shimano Inc. | Bicycle drive train |
US20210276663A1 (en) * | 2020-03-03 | 2021-09-09 | William W. Nelson | Kits to convert single-speed bicycles to multi-speed bicycles |
US20230264781A1 (en) * | 2022-02-18 | 2023-08-24 | Joseph Francis Keenan | System and method for bicycle transmission |
US11772743B2 (en) * | 2022-02-18 | 2023-10-03 | Joseph Francis Keenan | System and method for bicycle transmission |
US20230339572A1 (en) * | 2022-02-18 | 2023-10-26 | Joseph Francis Keenan | System and method for bicycle transmission |
Also Published As
Publication number | Publication date |
---|---|
JP4601480B2 (en) | 2010-12-22 |
NL1031375C2 (en) | 2007-11-14 |
TW200706451A (en) | 2007-02-16 |
CN1847082A (en) | 2006-10-18 |
JP2006298020A (en) | 2006-11-02 |
CN1847082B (en) | 2010-06-02 |
TWI290115B (en) | 2007-11-21 |
NL1031375A1 (en) | 2006-10-17 |
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Legal Events
Date | Code | Title | Description |
---|---|---|---|
AS | Assignment |
Owner name: HONDA MOTOR CO., LTD., JAPAN Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNORS:MATSUMOTO, SHINYA;SENDA, AKIO;REEL/FRAME:017838/0040 Effective date: 20060427 |
|
STCB | Information on status: application discontinuation |
Free format text: ABANDONED -- FAILURE TO RESPOND TO AN OFFICE ACTION |